CN101778465B - Error estimation based proportion power control method in CDMA (Code Division Multiple Access) cellular system - Google Patents

Abstract

The invention discloses an error estimation based proportion power control method in a CDMA cellular system, which comprises the following steps of: dialing by a mobile subscriber, transmitting signals to a base station; after the base station receives the signals, calculating a deference value of a target signal to interference ratio and a signal to interference ratio of the mobile subscriber according to different types, and transmitting the symbol of the difference value back to the mobile subscriber; after the mobile subscriber receives the symbol which is transmitted back, estimating the error of the signal to-interference ratio by using an estimation algorithm; substituting the error of the signal to interference ratio in a proportion power control algorithm to obtain a new proportion power control algorithm; and calculating a new signal transmission power of next time by the mobile subscriber according to the new proportion power control algolithm. The invention can be applied to a real CDMA cellular communication system. In an up-link, the mobile subscriber estimates the error of the signal interference ratio according to a 1-bit or 2-bit signalling transmitted back by the base station; and the invention can be applied to a self-adaption variable-step power control algorithm for adjusting transmission power.

Description

In the CDMA Cellular System based on the proportion power control method of estimation error

Technical field

The present invention relates in a kind of CDMA Cellular System to be applicable to the communications field based on the proportion power control method of estimation error.

Background technology

Cdma system is a kind of from the interference system, and capacity receives the influence of system self interference level.Control transmitting power effectively and can overcome near-far interference and multiple access interference well, and then improve power system capacity.In addition, power is the limited resources of communication system, how to satisfy under the more users QoS condition, and the transmitting power that reduces transmitting terminal as much as possible is exactly the key problem of power control.In recent ten years, power control problem causes people's extensive concern, and the researcher solves power control problem from different angles.Therefore along with the arrival in 3G epoch, CDMA technology has been widely used in the actual life, and good algorithm of performance needs fast convergence rate, realizes simply, the more important thing is that robustness is good, can adapt to complicated, the time communication environment that becomes.The purpose of this paper is exactly such power control algorithm of design.

J.M.Aein has proposed the balanced notion of signal interference ratio in the problem of management that research satellite communication system justice is disturbed, power control problem is converted into eigenvalue of maximum and the vectorial problem of character pair of asking a nonnegative matrix.J.Zander is applied to noiseless narrowband CDMA system with the signal interference ratio equalization methods, has proposed the Centralized Power Control algorithm of minimizing disruption probability.Centralized power control algorithm needs a large amount of system signaling information, is difficult to be applied to reality, and therefore, the distributed power control algolithm becomes the emphasis of research.J.Zander is ignoring proposition distributed signal interference ratio equalization algorithm (DBA) under the system background noise prerequisite.Foschini and Miljanic in provide background noise on the occasion of the cdma system model; Model more approaches reality; A kind of distributed power control algorithm (FMA) is proposed; Proved under system's feasible condition, no matter the synchronous or asynchronous refresh of transmitting power in the system receives signal interference ratio and all converges to fixing point.On FMA algorithm basis, Grandhi considers that maximum transmission power is limited, proposes distributed limited power control algolithm (DCPC).Simultaneously, Yates in provided the theoretical frame that up-link power control convergence is analyzed.Subsequently; Method according to iterative linear equation in the numerical linear algebra; Researchers have proposed a series of power control algorithms: the limited second order power control algorithm (CSOPC) of the representational Jantti of having R, Gauss Sai Deer iterative algorithm (CGS) of Lelic D or the like; Compare the DCPC algorithm, these Algorithm Convergences all increase.

The implementation of above algorithm all is based on two conditions: 1, link gain is changeless; 2, power control instruction can be got the arbitrary value of real domain.This is too Utopian in real system, and in wireless system, complicated communication environment becomes when making link gain, and power control instruction must be through the capacity constrained channels transmission.Therefore the algorithm that provides can't guarantee convergence in practical application, set optimization performance index are difficult to realize.

In the supposing the system link gain be at random, the time situation about becoming under; Receiving signal interference ratio, channel disturbance etc. is the stochastic variable of obeying certain distributed; Theoretical according to stochastic approximation, S.Ulukus, R.D.Yates obtain the power control algorithm at random based on matched filter output; Lijun Qian proposes to estimate the also power control algorithm at random of predicted channel variable based on Kalman filter.

In recent years, control theory also is applied to the solution of power control problem.Link gain be at random, time becomes; The control of CDMA closed power can be thought " the feedback power control system that band postpones " (DFPC), so correlation analysis and the designing technique of control theory in every field can be used for carrying out the analysis and the design of CDMA power control system.Along with game theoretic maturation, increasing related algorithm also occurs in succession.

Though above-mentioned power control algorithm is under the situation that link gain becomes at random the time, to provide; But only from the angle analysis power control loop of unique user; Implementation procedure is loaded down with trivial details, needs additional complicated prediction, algorithm for estimating, and the real-time of algorithm is bad; And the accurate feedback information of needs, the busy channel capacity.

Summary of the invention

The object of the invention is exactly in order to address the above problem the ratio power control algorithm based on estimation error of proposition.

For realizing above-mentioned purpose, the present invention has adopted following technical scheme:

This proportion power control method may further comprise the steps:

Step1: the mobile subscriber puts through phone, to base station transmit signals;

Step2: after the base station receives signal, calculate users' the target signal interference ratio and the difference of signal interference ratio according to dissimilar, and the quantitative information of described difference is returned to the mobile subscriber; The mobile subscriber receives the quantitative information of difference, estimates the signal interference ratio error according to algorithm for estimating;

Step3: in signal interference ratio error substitution ratio power control algorithm, obtain new ratio power control algorithm;

Step4: the mobile subscriber calculates the signal transmission power next time that makes new advances according to new ratio power control algorithm.

In described Step2, the base station is according to two kinds of dissimilar calculating users' the target signal interference ratio and the difference of signal interference ratio, and these two types comprise single-bit feeding back signaling and many bits feeding back signaling, utilizes algorithm for estimating to estimate the signal interference ratio error; In described Step3, the base station is dissimilar with in the signal interference ratio error substitution ratio power control algorithm according to two kinds, obtains new ratio power control algorithm.

When base station selected single-bit feeding back signaling, following algorithm for estimating estimation signal interference ratio error is adopted in the base station:

$\tilde{E}\left(k\right)=\frac{1}{2}[1+u\left(k\right)u(k-1)]\tilde{E}(k-1)+{\mathrm{\δ}}_{e}u\left(k\right),$

$\tilde{e}\left(k\right)={10}^{\tilde{E}\left(k\right)/10},$

Wherein, k representes k constantly, and k-1 representes k-1 constantly, u (k)=sign (E (k)), $E\left(k\right)={\mathrm{\Γ}}_i^{\mathrm{Tgt}}-{\mathrm{\Γ}}_i\left(k\right),$ Γ _i ^Tgt, Γ _i(k) be respectively target signal interference ratio and mobile subscriber's signal interference ratio of decibel form, E (k) is the signal interference ratio error,

Be the estimated value of signal interference ratio error, δ _eBe signal interference ratio error adjustment step-length, be constant, value is relevant with the signal interference ratio error range, gets δ here _e=0.5; $e\left(k\right)=\frac{{\mathrm{\γ}}_i^{\mathrm{Tgt}}}{{\mathrm{\γ}}_i\left(k\right)},$ Wherein, γ _i ^TgtBe given threshold value, γ _iCalculating follow following formula:

${\mathrm{\γ}}_i=\frac{g_{\mathrm{ii}}{p}_i}{{\mathrm{\Σ}}_{j=1,j\≠i}^Q{g}_{\mathrm{ij}}{p}_j+{\mathrm{\υ}}_i},i=1,...,Q,$

Wherein, Q representes that total Q is activated mobile subscriber, p _iThe transmitting power of expression mobile subscriber i, g _IjExpression mobile subscriber j is to the link gain of base station i, υ _iBe illustrated in the reception background noise of base station i.

When base station selected many bits feeding back signaling, the signal interference ratio estimation error algorithm that the single-bit feeding back signaling is adopted improves, and the algorithm for estimating after improving below adopt the base station is estimated the signal interference ratio error:

${\tilde{E}}_m\left(k\right)=\frac{1}{2}[1+u\left(k\right)u(k-1)]{\tilde{E}}_m(k-1)+\{\frac{1}{2}[1+u\left(k\right)u(k-1)]s\left(k\right)\mathrm{\δ}+{\mathrm{\δ}}_e\}u\left(k\right),$

${\tilde{e}}_m\left(k\right)={10}^{{\tilde{E}}_m\left(k\right)/10},$

Wherein, k representes k constantly, and k-1 representes k-1 constantly, $u\left(k\right)=\mathrm{Sign}({\mathrm{\Γ}}_i^{\mathrm{Tgt}}-{\mathrm{\Γ}}_i\left(k\right)),$ The information of s (k) for obtaining after using many bit informations that difference is quantized,

For using the algorithm for estimating after improving to obtain signal interference ratio error estimate, Γ _i ^Tgt, Γ _i(k) be respectively target signal interference ratio and mobile subscriber's signal interference ratio of decibel form, δ, δ _eBeing constant, is signal interference ratio error adjustment step-length, and value is relevant with the signal interference ratio error range, gets δ=0.1, δ here _e=0.5; $e\left(k\right)=\frac{{\mathrm{\γ}}_i^{\mathrm{Tgt}}}{{\mathrm{\γ}}_i\left(k\right)},$ Wherein, γ _i ^TgtBe given threshold value, γ _iCalculating follow following formula:

${\mathrm{\γ}}_i=\frac{g_{\mathrm{ii}}{p}_i}{{\mathrm{\Σ}}_{j=1,j\≠i}^Q{g}_{\mathrm{ij}}{p}_j+{\mathrm{\υ}}_i},i=1,...,Q,$

Wherein, Q representes that total Q is activated mobile subscriber, p _iThe transmitting power of expression mobile subscriber i, g _IjExpression mobile subscriber j is to the link gain of base station i, υ _iBe illustrated in the reception background noise of base station i.

In described Step3, when base station selected single-bit feeding back signaling, the signal interference ratio error does $\tilde{e}\left(k\right)={10}^{\tilde{E}\left(k\right)/10},$ The ratio power control algorithm is:

$p_i(k+1)=p_i\left(k\right)-\mathrm{\αf}(1-\frac{{\mathrm{\γ}}_i^{\mathrm{tgt}}}{{\mathrm{\γ}}_i\left(k\right)})p_i\left(k\right),i=1,...,Q,$

Function f (x) is the odd function that bound is arranged, for: $f\left(x\right)=-1+\frac{2}{1+e^{-\mathrm{\σ\; x}}},\mathrm{\σ}>0;$ In signal interference ratio error substitution ratio power control algorithm, obtain new power control algorithm:

$p_i(k+1)=p_i\left(k\right)-\mathrm{\αf}(1-\tilde{e}\left(k\right))p_i\left(k\right),i=1,...,Q.$

Wherein, Q representes that total Q is activated the mobile subscriber, and α representes the range parameter that each iteration transmission power value changes, 0＜α≤1; p _i(k) expression mobile subscriber i is at k power constantly, p _i(k+1) expression mobile subscriber i is at k+1 power constantly;

Estimated value for the signal interference ratio error.

In described Step3, when base station selected many bits feeding back signaling, the signal interference ratio error does ${\tilde{e}}_m\left(k\right)={10}^{{\tilde{E}}_m\left(k\right)/10},$ The ratio power control algorithm is:

$p_i(k+1)=p_i\left(k\right)-\mathrm{\αf}(1-\frac{{\mathrm{\γ}}_i^{\mathrm{tgt}}}{{\mathrm{\γ}}_i\left(k\right)})p_i\left(k\right),i=1,...,Q,$

Function f (x) is the odd function that bound is arranged, for: $f\left(x\right)=-1+\frac{2}{1+e^{-\mathrm{\σ\; x}}},\mathrm{\σ}>0;$ In signal interference ratio error substitution ratio power control algorithm, obtain new power control algorithm:

$p_i(k+1)=p_i\left(k\right)-\mathrm{\αf}(1-{\tilde{e}}_m\left(k\right))p_i\left(k\right),i=1,...,Q.$

Wherein, Q representes that total Q is activated the mobile subscriber, and α representes the range parameter that each iteration transmission power value changes, 0＜α≤1; p _i(k) expression mobile subscriber i is at k power constantly, p _i(k+1) expression mobile subscriber i is at k+1 power constantly;

Estimated value for the signal interference ratio error.

In described Step4, the mobile subscriber calculates the signal transmission power p next time that makes new advances according to new ratio power control algorithm _i(k+1).

The invention has the beneficial effects as follows: than traditional DCPC algorithm; New algorithm uses non-linear ratio's function---Sigmoid function, can adjust step-length by adaptively modifying power, and convergence rate is faster; Especially the time become under the link gain condition; New algorithm can be followed the tracks of the variation of link gain in real time, and algorithm stability is good, robustness is high, flexible letter environment when therefore being applicable at random more.New algorithm only needs 1bit or 2bit feedback information in the evaluated error process, and DCPC algorithm and need feed back accurate detection or information of forecasting based on the various algorithms of random theory and control theory, therefore, it is simple that new algorithm is realized, and shared channel capacity is few.In the time of in being applied to actual CDMA Cellular System, feedback channel has noise, and the new algorithm performance obviously is better than other algorithms.

Description of drawings

User's signal interference ratio change curve when Fig. 1 gets different value for ProPC algorithm α under the fixed link gain condition, σ=0.5;

Fig. 2 is user's signal interference ratio change curve when σ gets different value in the ProPC algorithm under the fixed link gain condition, α=0.3;

Fig. 3 is DCPC algorithm under the fixed link gain condition, FSPC algorithm, ProPC algorithm user signal interference ratio change curve;

Fig. 4 for the time become DCPC algorithm, ProPC algorithm user signal interference ratio change curve under the link gain condition;

Fig. 5 is EProPC algorithm under the fixed link gain condition, MEProPC algorithm user signal interference ratio change curve;

Fig. 6 is the DS-CDMA cellular system;

Fig. 7 is signal interference ratio error estimate and an actual value in the EProPC algorithm;

Fig. 8 is the cumulative distribution function curve (CDF) of user's signal interference ratio value, V _Max=5km/h;

Fig. 9 is many bit information passbacks cumulative distribution function curves (CDF) of user's signal interference ratio value down, V _Max=5km/h;

Figure 10 is the cumulative distribution function curve (CDF) of user's signal interference ratio value under the error condition, V _Max=5km/h.

Embodiment

Below in conjunction with accompanying drawing and embodiment the present invention is further specified.

Consider a cdma cellular communication system, N sub-district arranged in the system, total Q is activated the mobile subscriber.For each communication link, the pair of orthogonal channel is all mated to mobile subscriber's (down link) in (up link), base station from mobile subscriber to the base station.Owing to do not disturb between system up-link and the down link, only consider uplink channel power control problem, the gained conclusion can be applied to down link fully.

In cdma system, shared same channel of all users and different user can be connected to identical base station.Definition t is g by the link gain of base station under i the sub-district of m user in k the sub-district constantly _Ikm(t), three-dimensional matrice G _Ikm(t)={ g _Ikm(t) } be called as the uplink gain matrix of cdma system.The definition mapping: (k, m) → j, (1≤j≤Q),

$j=\underset{n=0}{\overset{k-1}{\mathrm{\Σ}}}{T}_n+m,1\≤m\≤T_k---\left(2.1\right)$

T wherein ₀=0, T _n(n=1,2 ..., N) be number of mobile users in the n of sub-district.Link gain g like this _Ikm(t) be mapped as g _Ij(t), (1≤i≤N, 1≤j≤Q), all g _Ij(t) form two-dimensional matrix G (t), i.e. G (t)={ g _Ij(t) }.Through above mapping, the link gain matrix reduction of cdma cellular communication system is a two-dimensional matrix.

In model, suppose that mobile subscriber i belongs to i base station, user's reception signal interference ratio is expressed as:

${\mathrm{\γ}}_i=\frac{g_{\mathrm{ii}}{p}_i}{{\mathrm{\Σ}}_{j=1,j\≠i}^Q{g}_{\mathrm{ij}}{p}_j+{\mathrm{\υ}}_i},i=1,...,Q---\left(2.2\right)$

P wherein _iThe transmitting power of expression mobile subscriber i, g _IjExpression mobile subscriber j comprises path fading, shadow fading, multipath fading and cdma system spreading gain to the link gain of base station i; υ _iBe illustrated in the reception background noise of base station i.

When mobile subscriber's signal interference ratio (SIR) is not less than given threshold value γ _i ^TgtThe time, think that just its signal is received by normal, that is:

${\mathrm{\γ}}_i=\frac{g_{\mathrm{ii}}{p}_i}{{\mathrm{\Σ}}_{j=1,j\≠i}^Q{g}_{\mathrm{ij}}{p}_j+{\mathrm{\υ}}_i}\≥{\mathrm{\γ}}_i^{\mathrm{tgt}},i=1,...,Q---\left(2.3\right)$

Be without loss of generality, definition normalization link gain matrix H is: $h_{\mathrm{Ij}}={\left[H\right]}_{\mathrm{Ij}}={\mathrm{\γ}}_i^{\mathrm{Tgt}}\frac{g_{\mathrm{Ij}}}{g_{\mathrm{Ii}}},$ h _Ii=0; Definition ${\mathrm{\η}}_i={\mathrm{\γ}}_i^{\mathrm{Tgt}}\frac{{\mathrm{\υ}}_i}{g_{\mathrm{Ii}}}.$ For the time become the link gain system, can suppose that H changes in time near average, k has in the moment:

H(k)＝H ^av+ΔH(k) (2.4)

H wherein ^Av(known or estimable) is the average of matrix H, Δ H (k) (the unknown) according to given distribution along with the iteration change at random.Be expressed as with element form: h _Ij(k)=h _Ij ^Av+ Δ h _Ij(k).Definition Δ h _Ij(k) maximum at moment k is: Δ _k=max| Δ h _Ij(k) |.

From angle consideration of power control problem a kind of simplification, that the time is continuous, can obtain following matrix form by formula (2.3):

(I-H)P＝η (2.5)

Wherein Q ties up column vector P={p _iExpression transmitting power vector; H is a normalization link gain matrix, does not consider its time variation; η is a noise vector, and I is a unit matrix.Finding the solution power control problem is exactly through observation γ _i ^Tgt, γ _i, p _iFind the solution formula (2.5), make power vector P converge on best transmit power vector P ^Opt, that is:

$P^{\mathrm{opt}}={(I-H)}^{-1}\mathrm{\η}\⇔{\mathrm{\γ}}_i={\mathrm{\γ}}_i^{\mathrm{tgt}},i=1,...,Q---\left(2.6\right)$

Under the link gain condition that at random the time, becomes, a kind of distributed fully, non-linear ratio's power control algorithm model is proposed.The algorithm general formula is following: each mobile subscriber i regulates through-put power by following rule constantly at k+1:

$p_i(k+1)=p_i\left(k\right)-\mathrm{\αf}(1-\frac{{\mathrm{\γ}}_i^{\mathrm{tgt}}}{{\mathrm{\γ}}_i\left(k\right)})p_i\left(k\right),i=1,...,Q---\left(\mathrm{3.1.1}\right)$

Wherein, α representes the range parameter that each iteration transmission power value changes, 0＜α≤1; Function f (x) is for there being the odd function of bound, can for:

$f\left(x\right)=\frac{1-a^{\mathrm{\θx}}}{1+a^{\mathrm{\θx}}},\mathrm{\θ}>0,a>1---\left(\mathrm{3.1.2}\right)$

Also can be the sigmoid function:

$f\left(x\right)=-1+\frac{2}{1+e^{-\mathrm{\σx}}},\mathrm{\σ}>0---\left(\mathrm{3.1.3}\right)$

Consider the situation of (3.1.3), (3.1.3) brought into (3.1.1), and to obtain power control algorithm iterative:

$p_i(k+1)=p_i\left(k\right)-\mathrm{\α}(-1+\frac{2}{1+e^{-\mathrm{\σ}(1-\frac{{\mathrm{\γ}}_i^{\mathrm{tgt}}}{{\mathrm{\γ}}_i\left(k\right)})}})p_i\left(k\right),i=1,...,Q---\left(\mathrm{3.1.4}\right)$

Be called the ProPC algorithm, wherein, σ＞0, along with the σ value increases, function f (x) steepen, algorithm the convergence speed accelerates; But when the σ value surpassed a certain numerical value, function f (x) was too precipitous, and each iterative power value changes too greatly, and algorithm is no longer restrained, therefore should be according to the value of system environments parameter acquiring σ.

Consider the bound restrictive condition of transmitting power, the iterative of ProPC algorithm can be expressed as:

$p_i(k+1)=\min \{p^{\max },\max \{0,p_i\left(k\right)-\mathrm{\α}(-1+\frac{2}{1+e^{-\mathrm{\σ}(1-\frac{{\mathrm{\γ}}_i^{\mathrm{tgt}}}{{\mathrm{\γ}}_i\left(k\right)})}})p_i\left(k\right)\left\}\right\},i=1,...,Q---\left(\mathrm{3.1.5}\right)$

P wherein ^MaxThe expression maximum transmission power.This algorithm application is in up link, and the base station is back to the mobile subscriber with detected mobile subscriber's signal interference ratio value γ i, and travelling carriage upgrades transmitting power according to algorithm iteration.

Up-link power control algolithm convergence problem proposes a framework, and promptly the power iteration function is necessary for canonical function, satisfies nonnegativity, monotonicity, three conditions of extensibility.

In order to verify that the ratio power control algorithm based on the sigmoid function restrains, and establishes function:

$g\left(p_i\left(k\right)\right)=p_i(k+1)=p_i\left(k\right)-\mathrm{\αf}(1-\frac{{\mathrm{\γ}}_i^{\mathrm{tgt}}}{{\mathrm{\γ}}_i\left(k\right)})p_i\left(k\right)$

$=p_i\left(k\right)-\mathrm{\α}(-1+\frac{2}{1+e^{-\mathrm{\σ}(1-\frac{{\mathrm{\γ}}_i^{\mathrm{tgt}}}{{\mathrm{\γ}}_i\left(k\right)})}})p_i\left(k\right),i=1,...,Q$

If g (x) is a canonical function, need satisfy following three conditions:

1) nonnegativity, i.e. g (x) >=0;

2) monotonicity, ${\∀x}_1\≥x_2,$ G (x is all arranged ₁)>=g (x ₂);

3) extensibility to constant μ＞1, has μ g (x) >=g (μ x).Conclusion: function g (x) is a canonical function.

Proof: order $1-\frac{{\mathrm{\&gamma;}}_i^{\mathrm{Tgt}}}{{\mathrm{\&gamma;}}_i\left(k\right)}=b,$ Then $g\left(x\right)=x-\mathrm{\&alpha;}(-1+\frac{2}{1+e^{-\mathrm{\&sigma;\; b}}})x,0<\mathrm{\&alpha;}\&le;1$ By 0＜α≤1, $-1<-1+\frac{2}{1+e^{-\mathrm{\&sigma;\; b}}}\&le;1,$ Can directly draw g (x)>=0, μ g (x)>=g (μ x), promptly g (x) satisfies nonnegativity, extensibility.Prove its monotonicity below:

Differentiate gets to function: $g^{\&prime;}\left(x\right)=1-\mathrm{\&alpha;}(-1+\frac{2}{1+e^{-\mathrm{\&sigma;\; b}}})+\mathrm{\&alpha;}\frac{{2e}^{-\mathrm{\&sigma;\; b}}}{{\mathrm{\&gamma;}}_i{(1+e^{-\mathrm{\&sigma;\; b}})}^2}$ Have g ' (x)＞0, this explanation g (x) is a monotonically increasing, thereby satisfies monotonicity.

In (3.1.4), order $e\left(k\right)=\frac{{\mathrm{\&gamma;}}_i^{\mathrm{Tgt}}}{{\mathrm{\&gamma;}}_i\left(k\right)},$ Its decibel form is expressed as

$E\left(k\right)={\mathrm{\&Gamma;}}_i^{\mathrm{tgt}}-{\mathrm{\&Gamma;}}_i\left(k\right)---\left(\mathrm{3.2.1}\right)$

Γ wherein _i ^Tgt, Γ _i(k) be respectively target signal interference ratio and mobile subscriber's signal interference ratio of decibel form, E (k) is called the signal interference ratio error.Because power control instruction is in the limited capacity channel, the base station needs the exact value γ of bulk information bit passback mobile subscriber signal interference ratio _i, therefore,, how to utilize simple back information to obtain the signal interference ratio error estimate at mobile client

It is the problem that we need solve.

Ownership goal signal interference ratio and signal interference ratio difference calculate in the place in the base station, and its symbol is returned to the mobile subscriber, need 1bit, are called the up-down instruction:

u(k)＝sign(E(k)) (3.2.2)

The mobile subscriber receives the up-down instruction, estimates the signal interference ratio error according to following algorithm for estimating:

$\tilde{E}\left(k\right)=\frac{1}{2}[1+u\left(k\right)u(k-1)]\tilde{E}(k-1)+{\mathrm{\&delta;}}_{e}u\left(k\right)---\left(\mathrm{3.2.3}\right)$

$\tilde{e}\left(k\right)={10}^{\tilde{E}\left(k\right)/10}---\left(\mathrm{3.2.4}\right)$

δ wherein _eBeing constant, is signal interference ratio error adjustment step-length, and value is relevant with the signal interference ratio error range, gets δ here _e=0.5.

In the ProPC algorithm, the signal interference ratio error is estimated, is obtained new power control algorithm (EProPC):

$p_i(k+1)=p_i\left(k\right)-\mathrm{\&alpha;f}(1-\tilde{e}\left(k\right))p_i\left(k\right),i=1,...,Q---\left(\mathrm{3.2.5}\right)$

Single-bit passback estimation error power control algorithm is improved; Ownership goal signal interference ratio and signal interference ratio difference E (k) calculate in the place in the base station; Use the multidigit bit information that difference is quantized; The quantitative information u (k) that obtains, s (k) (the required bit number of u (k) is 1, and the required bit number of s (k) is the constant more than or equal to 1) return to travelling carriage through forward channel.The mobile subscriber utilizes quantitative information, obtains signal interference ratio error estimate

definition according to improved algorithm for estimating:

$E\left(k\right)={\mathrm{\&Gamma;}}_i^{\mathrm{tgt}}-{\mathrm{\&Gamma;}}_i\left(k\right)---\left(\mathrm{3.2.6}\right)$

$u\left(k\right)=\mathrm{sign}({\mathrm{\&Gamma;}}_i^{\mathrm{tgt}}-{\mathrm{\&Gamma;}}_i\left(k\right))---\left(\mathrm{3.2.7}\right)$

$s\left(k\right)=\mathrm{Sign}(\mathrm{Abs}({\mathrm{\&Gamma;}}_i^{\mathrm{Tgt}}-{\mathrm{\&Gamma;}}_i\left(k\right))>\mathrm{\&alpha;})$ (2bit quantification) (3.2.8)

$s\left(x\right)=\left\{\begin{array}{cc}0,& |{\mathrm{\&gamma;}}_i^{\mathrm{TgtdB}}-{\mathrm{\&gamma;}}_i{\left(k\right)}^{\mathrm{DB}}|{\&le;\mathrm{\&alpha;}}_1\\ 1,& {\mathrm{\&alpha;}}_1<|{\mathrm{\&gamma;}}_i^{\mathrm{TgtdB}}-{\mathrm{\&gamma;}}_i{\left(k\right)}^{\mathrm{DB}}|\&le;{\mathrm{\&alpha;}}_2\\ 2,& {\mathrm{\&alpha;}}_2<|{\mathrm{\&gamma;}}_i^{\mathrm{TgtdB}}-{\mathrm{\&gamma;}}_i{\left(k\right)}^{\mathrm{DB}}|\&le;{\mathrm{\&alpha;}}_3\\ 3,& {\mathrm{\&alpha;}}_3<|{\mathrm{\&gamma;}}_i^{\mathrm{TgtdB}}-{\mathrm{\&gamma;}}_i{\left(k\right)}^{\mathrm{DB}}|\end{array}\right.$ (3bit quantification) (3.2.9)

α wherein, α ₁, α ₂, α ₃Be constant, the expression quantized level.

Improved algorithm for estimating is expressed as:

${\tilde{E}}_m\left(k\right)=\frac{1}{2}[1+u\left(k\right)u(k-1)]{\tilde{E}}_m(k-1)+\{\frac{1}{2}[1+u\left(k\right)u(k-1)]s\left(k\right)\mathrm{\&delta;}+{\mathrm{\&delta;}}_e\}u\left(k\right)---\left(\mathrm{3.2.10}\right)$

${\tilde{e}}_m\left(k\right)={10}^{{\tilde{E}}_m\left(k\right)/10}---\left(\mathrm{3.2.11}\right)$

δ wherein, δ _eBeing constant, is signal interference ratio error adjustment step-length, and value is relevant with the signal interference ratio error range, gets δ=0.1, δ here _e=0.5.

In the ProPC algorithm, adopting improved algorithm for estimating that the signal interference ratio error is estimated, obtain new power control algorithm---improved power control algorithm (MEProPC) is expressed as:

$p_i(k+1)=p_i\left(k\right)-\mathrm{\&alpha;f}(1-{\tilde{e}}_m\left(k\right))p_i\left(k\right),i=1,...,Q---\left(\mathrm{3.2.12}\right)$

Instance 1. is considered single sub-district cdma system, provides some simulation results based on the ratio power control algorithm (ProPC) of sigmoid function.Omni-base station is positioned at center of housing estate, and Q is arranged, and (Q=10) individual activation mobile subscriber, user are evenly distributed in the sub-district and shared same channel.Apread spectrum bandwidth is 1.2288MHz, and user data transmission speed is 9.6kbps (spreading gain equals 21dB).User i comprises path fading and shadow fading to the link gain of base station, is defined as:

$g_i=s_i{d}_i^{-\mathrm{\&beta;}}---\left(4.1\right)$

d _iBe the distance of i user to the base station; β is the path fading index, gets β=4 here; Shadow fading factor s _iObeys logarithm normal distribution [E (s _i)=0dB, σ (s _i)=8dB].All ownership goal signal interference ratio values are got 6dB, and the base station receives background noise and gets 10 ^-12W.Under the fixed link gain condition, Δ h _Ij(k)=0; For the time become link gain, Δ h _Ij(k) be modeled as obedience and go up equally distributed stochastic variable at interval [Δ, Δ].User's Initial Trans is the random value on interval [0,1].

Fig. 1, Fig. 2 have provided ProPC algorithm constringency performance under different parameters is provided with respectively and have compared; α is the range parameter that transmission power value changes in the iterative process; As can beappreciated from fig. 1: if α value too small (α=0.1); Each iterative power change value is little, needs repeatedly iteration just can converge to optimal transmit power; If α value excessive (α=1), each iterative power change value is bigger, and the iteration initial stage is in oscillatory regime, and needing repeatedly iteration just can converge to equally has most transmitting power power; α=0.3rd, suitable.The steep of parameter σ representative function f (x), σ is big more, and f (x) is precipitous more, and each iterative power changing value is big more, and σ is more little, and f (x) is mild more, and each iterative power changing value is more little; As can be seen from the figure, σ=0.5th, suitable.

Fig. 3 adopts DCPC algorithm, FSPC algorithm algorithm as a comparison, has provided ProPC algorithm (Δ under the fixed link gain condition _k=0) user's signal interference ratio change curve, Fig. 4 adopts DCPC algorithm algorithm as a comparison, provided the ProPC algorithm the time become (Δ under the link gain condition _k=0.1) user's signal interference ratio conversion curve.Curve shows that the ProPC algorithm has better convergence, and the time change situation under robustness better.

Fig. 5 provides user's signal interference ratio change curve in EProPC algorithm, the MEProPC algorithm, can be known by figure, and the algorithm that this paper proposes is restrained, and wherein the required iterations of MEProPC algorithm than EProPC algorithm still less.

Instance 2: consider the cellular communication system of sub-district DS-CDMA more than, provide based on the ratio power control algorithm (EProPC) of estimation error and some simulation results of improvement algorithm (MEProPC algorithm) thereof.Have 19 sub-districts in system's (shown in Figure 6), omni-base station is positioned at the center of sub-district, and Q is arranged, and (Q=190) individual activation mobile subscriber is evenly distributed in the system, and apread spectrum bandwidth is 1.2288MHz, and user data transmission speed is 9.6kbps (spreading gain equals 21dB).The distribution link power attenuation is modeled as and comprises large scale path fading, shadow fading and Rayleigh fading.Path fading and user are to the distance dependent of base station, and the path fading index is β=4; Shadow fading factor si obeys logarithm normal distribution [E (s _i)=0dB, σ (s _i)=8dB]; Rayleigh fading produces according to the jakes model, and carrier frequency is 1950MHz, user's gait of march (km/h) interval [0, V _Max] last random valued, V _MaxFor the maximum gait of march of user, suppose that at the power control period, user's gait of march is constant.The power control frequency is 1500Hz.Do not consider the soft handover problem, the user communicates with the corresponding base station of maximum signal interference ratio value that is received.For the correct user profile that receives, all ownership goal signal interference ratio values are got 6dB, and the base station receives background noise and gets 10 ^-12W.User's Initial Trans is the random value on interval [0,1].

Use the cumulative distribution function (CDF) of Monte Carlo method computer center community user signal interference ratio value, carry out 200 times and independently move emulation, each duration is 1s (1500 power control period).

Fig. 7 is based in the ratio power control algorithm (EProPC) of estimation error, and signal interference ratio error actual value and estimated value comparison curves can find out that by figure this algorithm for estimating can be followed the tracks of the signal interference ratio error change preferably.

Fig. 8 is given in V _MaxAdopt the cumulative distribution function curve of center cell user's signal interference ratio that the EProPC algorithm obtains during=5km/h, provide the correlation curve of FSPC algorithm simultaneously.Can see from Fig. 8, compare the FSPC algorithm, use the 1bit back information equally, the performance of EProPC algorithm has raising greatly.Fig. 8 gives the correlation curve of ProPC algorithm and DCPC algorithm, and the ProPC convergence is higher than the DCPC algorithm.

Fig. 9 provides the EProPC algorithm and improves algorithm---the performance of MEProPC algorithm.The EProPC algorithm uses the 1bit back information, and the MEProPC algorithm uses 2bit back information at least, among the figure emulation back information bit be the situation of 2bit and 3bit.Can know that by curve among the figure many bits MEProPC algorithm has had bigger improvement to the EProPC algorithm performance, but after information bit surpassed 2bit, performance strengthened few.

Figure 10 is given under the situation of power control instruction error code (error rate gets 5%), the performance of EProPC algorithm, MEProPC algorithm.The contrast algorithm is FSPC algorithm, DCPC algorithm.The error rate=5% is arranged in the FSPC algorithm equally; The exact value that the DCPC algorithm needs the base station to send signal interference ratio to the mobile subscriber is introduced noise in transmission course, be modeled as variance and be 2 white Gaussian noise.Can know that by image the DCPC algorithm performance reduces more under the noise circumstance; FSPC algorithm, EProPC algorithm performance change little; The new algorithm robustness is higher than the DCPC algorithm far away, and in real system, the EProPC algorithm has great advantage because of it is realized easily, convergence is good.

Claims (2)

1.CDMA based on the proportion power control method of estimation error, it is characterized in that in the cellular system: this proportion power control method may further comprise the steps:

Step1: the mobile subscriber puts through phone, to base station transmit signals;

Step2: after the base station receives signal, calculate users' the target signal interference ratio and the difference of signal interference ratio according to dissimilar, and the quantitative information of described difference is returned to the mobile subscriber; The mobile subscriber receives the quantitative information of difference, estimates the signal interference ratio error according to algorithm for estimating;

Step3: in signal interference ratio error substitution ratio power control algorithm, obtain new ratio power control algorithm;

Step4: the mobile subscriber calculates the signal transmission power next time that makes new advances according to new ratio power control algorithm;

Among the described Step2, the base station is according to two kinds of dissimilar calculating users' the target signal interference ratio and the difference of signal interference ratio, and these two types comprise single-bit feeding back signaling and many bits feeding back signaling, utilizes algorithm for estimating to estimate the signal interference ratio error; In described Step3, the base station is dissimilar with in the signal interference ratio error substitution ratio power control algorithm according to two kinds, obtains new ratio power control algorithm;

When base station selected single-bit feeding back signaling, following algorithm for estimating estimation signal interference ratio error is adopted in the base station:

$\tilde{E}\left(k\right)=\frac{1}{2}[1+u\left(k\right)u(k-1)]\tilde{E}(k-1)+{\mathrm{\&delta;}}_{e}u\left(k\right),$

$\tilde{e}\left(k\right)={10}^{\tilde{E}\left(k\right)/10},$

Wherein, K representes that k constantly; K-1 representes that k-1 constantly; U (k)=sign (E (k)),

Be respectively target signal interference ratio and mobile subscriber's signal interference ratio of decibel form, E (k) is the signal interference ratio error,

Be the estimated value of signal interference ratio error, δ _eBe signal interference ratio error adjustment step-length, be constant, value is relevant with the signal interference ratio error range, gets δ here _e=0.5;

Wherein, Be given signal interference ratio threshold value, signal interference ratio γ _iCalculating follow following formula:

${\mathrm{\&gamma;}}_i=\frac{g_{\mathrm{ii}}{p}_i}{{\mathrm{\&Sigma;}}_{j=1,j\&NotEqual;i}^Q{g}_{\mathrm{ij}}{p}_j+{\mathrm{\&upsi;}}_i},$ i＝1，...，Q

Wherein, Q representes that total Q is activated mobile subscriber, p _iThe transmitting power of expression mobile subscriber i, g _IjExpression mobile subscriber j is to the link gain of base station i, υ _iBe illustrated in the reception background noise of base station i;

When base station selected many bits feeding back signaling, the signal interference ratio estimation error algorithm that the single-bit feeding back signaling is adopted improves, and the algorithm for estimating after improving below adopt the base station is estimated the signal interference ratio error:

${\tilde{E}}_m\left(k\right)=\frac{1}{2}[1+u\left(k\right)u(k-1)]{\tilde{E}}_m(k-1)+\left\{\frac{1}{2}\right[1+u\left(k\right)u(k-1)]s\left(k\right)\mathrm{\&delta;}+{\mathrm{\&delta;}}_e\}u\left(k\right),$

${\tilde{e}}_m\left(k\right)={10}^{{\tilde{E}}_m\left(k\right)/10},$

Wherein, k representes k constantly, and k-1 representes k-1 constantly,

The information of s (k) for obtaining after using many bit informations that difference is quantized,

For the algorithm for estimating after the use improvement obtains the signal interference ratio error estimate,

Γ _i(k) be respectively target signal interference ratio and mobile subscriber's signal interference ratio of decibel form, δ, δ _eBeing constant, is signal interference ratio error adjustment step-length, and value is relevant with the signal interference ratio error range, gets δ=0.1, δ here _e=0.5; Wherein,

Be given signal interference ratio threshold value, signal interference ratio γ _iCalculating follow following formula:

${\mathrm{\&gamma;}}_i=\frac{g_{\mathrm{ii}}{p}_i}{{\mathrm{\&Sigma;}}_{j=1,j\&NotEqual;i}^Q{g}_{\mathrm{ij}}{p}_j+{\mathrm{\&upsi;}}_i},$ i＝1，...，Q，

Wherein, Q representes that total Q is activated mobile subscriber, p _iThe transmitting power of expression mobile subscriber i, g _IjExpression mobile subscriber j is to the link gain of base station i, υ _iBe illustrated in the reception background noise of base station i;

Among the described Step3; When base station selected single-bit feeding back signaling, the signal interference ratio error for

ratio power control algorithm is:

$p_i(k+1)=p_i\left(k\right)-\mathrm{\&alpha;f}(1-\frac{{\mathrm{\&gamma;}}_i^{\mathrm{tgt}}}{{\mathrm{\&gamma;}}_i\left(k\right)})p_i\left(k\right),$ i＝1，...，Q，

Function f (x) is the sigmoid function, for:

σ＞0; In signal interference ratio error substitution ratio power control algorithm, obtain new power control algorithm:

$p_i(k+1)=p_i\left(k\right)-\mathrm{\&alpha;f}(1-\tilde{e}\left(k\right))p_i\left(k\right),$ i＝1，...，Q

Wherein, Q representes that total Q is activated the mobile subscriber, and α representes the range parameter that each iteration transmission power value changes, 0＜α≤1; p _i(k) expression mobile subscriber i is at k power constantly, p _i(k+1) expression mobile subscriber i is at k+1 power constantly;

Estimated value for the signal interference ratio error;

In described Step3; When base station selected many bits feeding back signaling, the signal interference ratio error for

ratio power control algorithm is:

$p_i(k+1)=p_i\left(k\right)-\mathrm{\&alpha;f}(1-\frac{{\mathrm{\&gamma;}}_i^{\mathrm{tgt}}}{{\mathrm{\&gamma;}}_i\left(k\right)})p_i\left(k\right),$ i＝1，...，Q，

Function f (x) is the sigmoid function, for:

σ＞0; In signal interference ratio error substitution ratio power control algorithm, obtain new power control algorithm:

$p_i(k+1)=p_i\left(k\right)-\mathrm{\&alpha;f}(1-{\tilde{e}}_m\left(k\right))p_i\left(k\right),$ i＝1，...，Q

Wherein, Q representes that total Q is activated the mobile subscriber, and α representes the range parameter that each iteration transmission power value changes, 0＜α≤1; p _i(k) expression mobile subscriber i is at k power constantly, p _i(k+1) expression mobile subscriber i is at k+1 power constantly;

Estimated value for the signal interference ratio error.

2. based on the proportion power control method of estimation error, it is characterized in that in the CDMA Cellular System according to claim 1: in described Step4, the mobile subscriber calculates the signal transmission power p next time that makes new advances according to new ratio power control algorithm _i(k+1).

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